I have a few ideas floating in the noggin about completing principles we bring to ministry. Matters that shape an approach, either-or choices we make in events/relationships/planning/life. It's because they are either-or that I picked a running title poles apart. I hope for a series of brief reflections.
That's the general intro. Much better now to get into it and you can see what I mean.
together-separate
Here's today's point, in simple terms: it's good when groups gather to be together, it's unhealthy when they gather to be separate.
I reckon that a Christian group gathers (properly) with much in common: a common Lord, Jesus; a common purpose, variable. Purposes could be prayer and Bible study; planning Sunday School, grief counselling, relationship-building, explaining the gospel to enquirers, ... You get the idea. These are all together reasons (a.k.a. fellowship).
Yet I see Christians gather sometimes just to be apart from other people. I remember the long-term Bible study group (over a decade old, I think) whose reputation was that Monday night was time to discuss everything bad about Sunday morning. I heard about a youth group whose leader wanted to show that he was not a boring as the other church leaders. I recall the guy doing ministry training for youth but who had very little respect for the rest of that church's youth ministry. In all these cases, and others like them, the group grew apart from the rest of the ministry. They were better/more faithful/on track. To them, others were beyond change/empty/fruitless.
On the surface, the two styles of group don't look different. A Bible study group is a Bible study group. The attitude, however, is poles apart. Togetherness is love and mutual concern - separation is sanctimonious superiority.
So when running a high school age group, run a fantastic group! But don't use it to run down all the other age groups. And when you lead a specific cultural ministry (Chinese-speakers, Indian origin, ...) use the power of what's in common for that group. But don't do it in order to get away from the cultures you don't like.